When flying at high altitude, the aircraft may encounter icing conditions. More specifically, ice may form on the skin and on the appendages of the aircraft. The appearance of ice is particularly problematical for aerodynamic probes the profiles of which may become altered by ice and the pressure tapping orifices of which may become blocked.
One solution to avoiding the formation of ice is to heat the appendages. At the present time, heating is mostly performed using electrical resistances embedded in the appendages. Heating is achieved through joule effect. For example, in order to heat a total-pressure probe, it is necessary to dissipate several hundred watts. More specifically, this type of probe is formed of a mast bearing a tube that is closed at one end and known as a Pitot tube. Heating the probe is achieved using a heating resistance produced in the form of a heating wire wound in the body of the probe, namely both in the mast and in the Pitot tube. In order to create the heating wire use is commonly made of an electrical conductor containing an alloy of iron and of nickel coated in an inorganic insulator such as alumina or magnesia. The insulator is itself coated with a sheath of nickel or of inconel to allow wire to be soldered to the body of the probe. One method for producing such a probe is, for example, described in patent application FR 2 833 347 filed in the name of the Applicant Company.
Creating the heating wire and assembling it to the probe entail a series of complex and expensive operations.
Another way of heating a Pitot tube probe has been conceived of in patent U.S. Pat. No. 4,275,603. That document describes the use of a heat pipe supplying thermal energy around the tube. The return of the heat-transfer fluid to the liquid state is brought about in a porous material. That allows the probe to be arranged in any possible orientation on the skin of the aircraft. In practice, that solution offers no industrial advantage because of the difficulty there is in inserting a porous material into a probe. In addition, the use of a porous material requires the zone of the heat pipe at which evaporation takes place and the condensation zone to be close to one another. This is why this probe comprises a heating wire positioned in the mast of the probe as close as possible to the Pitot tube. If the evaporation zone were situated further away, the heat pipe would suffer from a loss of priming. As a result, the method of producing such a probe is more complex than the method of using only a heating wire. Specifically, in such a probe, it is necessary for both the heating wire and the heat pipe to be outside the skin of the aircraft.